1. Field of the Invention
The present invention concerns a skin condition observation apparatus having a sebum amount measuring device for optically measuring the amount of deposited sebum by being in contact with skins.
2. Statement of Related Art
A sebum amount measuring device is used for recognizing the conditions of a customer's skins objectively, for example, in a so-called cosmetic salon (cosmetic shop). Since shop attendants can advice cosmetics optimal to the skin conditions based on the result of the observation and the customer is provided with objective data for purchasing such cosmetics, the device is extremely effective for the sales promotion.
Existent sebum amount measuring devices were used by attaching a disposable sebum sampling part made of plastics to the top end of a probe, putting the same on skins to deposit sebum and then measuring the intensity of a reflection light or a transmission light from the sebum deposited on the part and measuring the amount of sebum based on the result of the measurement.
In a case of using a disposable sebum sampling part, since the sebum can always be deposited on a new sebum sampling part, maintenance after use is not required and the sebum can be measured accurately with no maintenance on every measurement in a busy shop situation.
As described above, while the disposable part is convenient, since it has to be replaced with new sebum sampling part on every measurement and used part has to be discarded, running cost is increased to result in an economical disadvantage and it increases the volume of wastes. In addition, since the measurement is impossible if the part run out, parts have to be stocked always by a predetermined amount.
In view of the above, it has been proposed a device not requiring consumable parts at all although requiring some maintenance operation such as wiping off the sebum deposited on the sebum sampling surface (refer to Japanese Patent Laid-Open No. 2002-85356).
FIG. 4 shows the measuring method of such a sebum amount measuring device 51, in which the surface of a glass block 52 is formed as a sebum sampling surface 53, and a light incident surface 55 for incidence of a light illuminated from a light emitting element 54 to the sebum sampling surface 53 and a light emitting surface 57 for emission of a light reflected on the sebum sampling surface 53 to a photoreceiving element 56 are formed at the back of the block.
The incident angle of the light to the sebum sampling surface 53 is selected such that it is larger than a critical angle relative to water and smaller than a critical angle relative to sebum. For example, the light emitting element 54 is disposed on an incident optical axis 58 at an incident angle of 50°, and the surface is chamfered such that the light incident surface 55 is in perpendicular to the incident light axis 58. Further, the photoreceiving element 56 is disposed on a reflection light axis 59 at a reflection angle of 50°, and the light emitting surface 57 is chamfered such that it is in perpendicular to the reflection light axis 59.
According to the constitution described above, since the incident angle of the light is selected such that it is larger than the critical angle relative to water and smaller than the critical angle relative to sebum, even when sebum and water are deposited simultaneously on the sebum sampling surface 53, only the total reflection light from the sebum component reaches the photoreceiving device, while the light illuminated to the water component is transmitted with no reflection, so that the amount of the sebum can be measured accurately.
Further, since sebum and water can be removed simply from the sebum sampling surface 53 formed to the glass block 52 by merely wiping off with an alcohol or the like, disposable consumable parts such as the existent sebum sampling part are no more necessary.
However, since the incident light axis 58 and the reflection light axis 59 formed at an angle of 100° are not actually visible, it is extremely difficult to accurately position such that the optical axes 58 and 59 and the optical axes for the light emitting element 54 and the photoreceiving element 56 are aligned, as well as it is also difficult to form the light incident surface 55/light emitting surface 57 at the angle in accordance with the incident angle/reflection angle on the back of the glass block 52. Since fabrication accuracy is required in any of the cases, this results in a problem of increasing the manufacturing cost.
Further, since the light emitting element 54 and the photoreceiving element 56 are disposed on both right and left sides of the glass block 52 while sandwiching the block, the size of the sensor portion is enlarged to result in a problem that it can not be installed at a narrow.
In view of the above, it is a technical subject of the present invention, at first, to save requirement for glass fabrication at high accuracy or troublesome alignment between optical axes, and to enable size reduction for the sensor portion of a sebum amount measuring device and, secondly, provide a small sized skin condition observation apparatus incorporated with a sebum amount measuring device.